1. Plasma Levels of Levodopa and Its Main Metabolites in Parkinsonian Patients after Conventional and Controlled-Release Levodopa-Carbidopa Associations
- Author
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Gabriella Zara, Mario Furlanut, Eid Hassan, Massimo Baraldo, and P. Benetello
- Subjects
Male ,Levodopa ,medicine.medical_specialty ,3,4-Dihydroxyphenylacetic acid ,Dopamine ,Metabolite ,Antiparkinson Agents ,chemistry.chemical_compound ,Internal medicine ,Blood plasma ,medicine ,Humans ,Aged ,Neurologic Examination ,Dose-Response Relationship, Drug ,business.industry ,Homovanillic acid ,Area under the curve ,Carbidopa ,Homovanillic Acid ,Parkinson Disease ,Middle Aged ,Drug Combinations ,Endocrinology ,Neurology ,chemistry ,Blood-Brain Barrier ,Delayed-Action Preparations ,3,4-Dihydroxyphenylacetic Acid ,Tyrosine ,Female ,Neurology (clinical) ,business ,medicine.drug - Abstract
The paper reports plasma levels of levodopa (LD), its main metabolites [dopamine, dihydroxyphenylacetic acid, homovanillic acid, 3-O-methyldopa (3-O-MD)] and carbidopa in 14 parkinsonian patients first treated with Sinemet and thereafter with Sinemet-CR4. A good relationship was observed between LD plasma levels and pharmacological effects. While the LD area under the curve increased after Sinemet-CR4, the same was not observed with metabolites, except with 3-O-MD. The experiments in volunteer subjects confirmed the increase in 3-O-MD in plasma after Sinemet-CR4. Higher levels were observed also in the CSF with a reduction of LD concentrations. This seems to corroborate the hypothesis of an interference with LD passage through the blood-brain barrier in humans.
- Published
- 1993
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